Myliobatinae

Cicimurri, David J. & Knight, James L., 2009, Late Oligocene sharks and rays from the Chandler Bridge Formation, Dorchester County, South Carolina, USA, Acta Palaeontologica Polonica 54 (4), pp. 627-647 : 640

Subfamily Myliobatinae

Myliobatinae gen. indet.

Fig. 6B, C .

Referred specimens.—BCGM 9114–9117, SC 2009.18.22.

Comments.—Our sample is represented by partial medial teeth and complete lateral teeth (i.e., Fig. 6B ). The lingual ornamentation of each specimen is identical, and we believe that the fossils are conspecific. The preserved lateral margin on one medial tooth is weakly angular, indicating articulation with a lateral tooth ( Fig. 6C ). The dentition of Aetobatus Blainville, 1816 lacks lateral teeth and there is no indication of lateral angles on medial teeth (see Cappetta 1987).

The lingual crown ornamentation and morphology of lateral teeth in our sample are very similar to specimens identified as Myliobatis (sensu lato) sp. 2 from the Rupelian of Germany ( Reinecke et al. 2001: pl. 57b, d) and as Myliobatis oligocaena Leriche, 1910 from the French Rupelian ( Baut and Génault 1999: pl. 7: 2, 4), and these remains may be conspecific. Myliobatis oligocaena has been tentatively synonymized with Weissobatis micklichi Hovestadt and Hovestadt−Euler, 1999 , a taxon from the German Rupelian known from partial skeletons and articulated dentitions. The crown ornamentation and morphology of the lingual transverse ridge at the crown/root junction is close to Miocene material identified as Pteromylaeus Garman, 1908 by Cappetta (1970), but our medial teeth do not appear to have been as highly curved and our lateral teeth are not nearly as mesio−distally narrow as in extant Pteromylaeus (see Hovestadt and Hovestadt−Euler 1999: 343). Lateral teeth of Myliobatis Cuvier, 1816 and W. micklichi have been described as being lozenge−shaped in occlusal view ( Hovestadt and Hovestadt−Euler 1999: 343), and the lateral tooth of M. oligocaena illustrated by Baut and Génault (1999: pl. 7: 4) certainly appears to be so. Our two lateral teeth are less wide than long, but they appear to be within the range of the lateral−most row of teeth in W. micklichi (see Hovestadt and Hovestadt−Euler 1999: fig. 6). Hovestadt and Hovestadt−Euler (1999: 343) stated that attribution of isolated teeth to species of Myliobatis and Weissobatis Hovestadt and Hovestadt−Euler, 1999 should be avoided, and we follow this advice until more complete fossils are found.

Figures

Fig. 6. Batoids from Summerville, upper Chattian. A. Rhynchobatus pristinus (Probst, 1877), BCGM 9085, occlusal view. B, C. Myliobatinae gen. indet. B. BCGM 9117, lateral tooth, occlusal view. C. BCGM 9116, partial medial tooth, occlusal (C1) and lingual (C2) view. D. Paramobula fragilis (Cappetta, 1970), BCGM 9113, anterolateral tooth, occlusal (D1), labial (D2), and lateral (D3) view. E, F. Plinthicus stenodon Cope, 1869. E. BCGM 9120, partial anterior tooth, lateral (E1) and lingual (E2) view. F. BCGM 9121, lateral tooth, lateral (F1) and labial (F2) view. G. Rhinoptera cf. R. studeri (Agassiz, 1843), BCGM 9123, occlusal (G1) and lingual (G2) view. H. Gymnura sp., BCGM 9107, lateral (H1) and labial (H2) view.